The odds of winning will be (winning caps) : (number of non-winning bottles), then
[tex]4\colon16[/tex]We must simplify it, if we divide both by 4 we get
[tex]\frac{4}{4}\colon\frac{16}{4}[/tex]Then
[tex]1\colon4[/tex]That's the odds in favor of winning the prize in the contest